Background
Peak expiratory flow rate (PEFR) reflects the strength and condition of respiratory muscles and the degree of airflow limitation in large airways. PEFR shows hour-to-hour variation that follows a specific pattern in asthmatics and in healthy individuals. Adequate data are not available on the diurnal variation in normal individuals who are students in professional courses and living a sedentary lifestyle. Hence, this study was undertaken to study the diurnal variation in PEFRs in healthy men in South India.
Participants and methods
PEFR was recorded in 50 adult healthy male students who were nonsmokers, between 18 and 23 years of age and studying in professional courses (MBBS, BDS, Nursing and MSc). Mini Wright's peak flow meter was used to measure the PEFR. PEFRs were recorded at 7-8 a.m., 10-11 a.m., 1-2 p.m., 4-5 p.m. and 7-8 p.m. for 2 consecutive days.
Results
On analysis of PEFR records of each individual, it was seen that there was an overall dip in the morning at 7-8 h PEFR, which increased during the daytime, peaking in the afternoon at 4-5 p.m. and eventually decreased in the night. Participants did not show the peak PEFR values at the same time point: 16% of participants had a rise in PEFR in the early morning hours; afternoon (1-2 p.m.) peak was observed in 22% of participants; and evening (4-5 p.m.) peak was observed in 36% of participants. Only 2% of participants showed a peak in the night time (7-8 p.m.) PEFR values.
Conclusion
This study provided the preliminary reference data of diurnal variation of PEFR in healthy adults. As there is a variation in the PEFR recorded during different time points of the day, it is advisable to record the PEFR at the same time point to compare the PEFR between individuals.